CODEWITHSUNDEEP
regex
coderrr
coderrr

Reputation: 67

Password validation using regular expressions

I am trying to validate a password with the following rules:

So far I wrote this code: 

[0-9a-zA-Z] (?=(.*\d){2}) {8,}

Im not sure why the passwords I enter returns invalid although it follows the rules.

Upvotes: 0

Views: 66

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626926

Remember that spaces are meaningful in a regex pattern, so you require at least 8 spaces at the end. There are no anchors in the regex, so the length limitation might not work even if you write a correct pattern. So far, this will match an alphanumeric, a space that is followed with 2 occurrences of any 0+ chars followed with a digit, but since there is space with {8,} quantifier, this pattern will never match anything.

You need

^(?=.{8})[a-zA-Z]*(?:\d[a-zA-Z]*){2}[a-zA-Z0-9]*$

See the regex demo

  • ^ - start of string
  • (?=.{8}) - at least 8 chars
  • [a-zA-Z]* - zero or more letters
  • (?:\d[a-zA-Z]*){2} - 2 sequences of:
    • \d - a digit (may be replaced with [0-9])
    • [a-zA-Z]* - zero or more letters
  • [a-zA-Z0-9]* - 0+ alphanumeric chars
  • $ - end of string.

Alternatively, you may use

^(?=(?:[a-zA-Z]*\d){2})[a-zA-Z0-9]{8,}$

See another regex demo

Here, (?=(?:[a-zA-Z]*\d){2}) will require at least 2 occurrences of 0+ letters followed with a digit in the string and [a-zA-Z0-9]{8,} will match 8 or more alphanumeric chars.

Upvotes: 1

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